The present invention relates to housings of pumps and like devices which are used for conveying sand, gravel and/or other flowable solid or liquid substances which are likely to affect the integrity of the housing as a result of pronounced wear, erosion, washout, cavitation and/or other factors or influences. More particularly, the invention relates to such housings as well as to a method and an apparatus for repairing damages which arise in such housings as a result of the aforediscussed influences.
Pumps which are used in gravel pits and elsewhere to convey sand, gravel or like materials, normally in admixture to water or another suitable carrier fluid, are subject to extensive wear as a result of repeated pronounced rubbing contact with the particles of conveyed material. The wear is particularly pronounced in certain portions of the pump housing, and such portions develop recesses which can constitute mere cavities in the material-contacting internal surface or holes which extend all the way between the internal and external surfaces of the housing. As a rule, the housing of a sand pump is a casting which cannot be readily repaired by welding or an analogous material-adding technique. Therefore, the useful life of such housings is determined by the dimensions of the recess or recesses in the material-contacting surface of the housing. The housing must be discarded as soon as the dimensions of the recess are such that the recess allows conveyed material to escape from the housing in a region other than the intended outlet or outlets, or that the recess accumulates a quantity of material which interferes with the flow of freshly admitted material through the housing. In many instances, the entire pump must be discarded when the housing is discarded with attendant high costs for removal of a useless pump, purchase of a new pump, and installation of the new pump.
It was already proposed to resurface a damaged (pitted) housing by resort to build-up welding or similar techniques. The welding operation should result in the deposition of a substantial quantity of material in the recess, and the surplus of the welded-on material is to be removed by grinding. Such proposals have met with no success and have failed to gain acceptance by the manufacturers and/or users of sand pumps or the like because a cast metal, of which the housings of such devices are normally made, does not retain the material which is to be added thereto by build-up welding.